Unit A: Nervous and Endocrine Systems PDF

Nervous & Endocrine Systems Biology 30 Diploma Prep 20-25% of Diploma Questions  Nervous System Nervous System Organizational Tree! Central Nervous System Peripheral N...

Nervous & Endocrine Systems Biology 30 Diploma Prep 20-25% of Diploma Questions  Nervous System Nervous System Organizational Tree! Central Nervous System Peripheral Nervous (CNS) System (PNS) Decision maker Feeds into & out of CNS Sensory Pathway Motor Pathway Brain & Spinal Cord Somatic Pathway Autonomic Pathway (Voluntary) (Involuntary) under conscious control unconscious control Examples? Examples? Sympathetic Parasympathetic (Stimulatory) (Restores to normal) Speeds you up! Restores balance! Excites you! Restores Homeostasis! 5 major components Stimulus -highly specific receptor -receive stimuli Sensory Pathway modulator/regulator Motor Pathway -carries out the response effector (muscle or gland) Action Nerves versus Neurons Three Types of Neurons 1. Motor - Carries information from the CNS to the effectors (muscles/glands). Located in the PNS 2. Sensory - Carries information a sensory receptor to the CNS. Located in the PNS 3. Interneuron Connect sensory neurons to motor neurons Connects two or more neurons Found in CNS **Glial Cells – nourish the neurons, remove waste and defend against infection. Outnumber neurons 10 to 1. Structures of Neuron Dendrites Pick up impulses from previous neuron and carry to the cell body Cell Body Produces many chemicals needed by the neuron Preforms metabolism Axon Carries impulses from the cell body to the synapse Functions to insulate the axon thus increasing speed of transmission Axon In the CNS, oliogodendrocytes form the fatty white myelin sheath forms around the axon In the PNS, Schwann Cells form the fatty white myelin sheath by wraping around the axon. As each Schwann cell wraps around the nerve fiber, its nucleus and cytoplasm are squeezed to the perimeter to form the neurilemma The function of the neurilemma is the regeneration of nerves Myelin Sheath Structures of Neuron Nodes of Ranvier Gaps between the myelin sheath Impulses jump from one node to the next during Saltatory conduction Synapse Junction between the pre-synaptic neuron and the post-synaptic neuron Synaptic knobs contain Vesicles that release the neurotransmitter aceylcholine Mitochondria to produce ATP for neurotransmitter synthesis Synapse Reflex Arc Occurs without brain involvement or conscious thought Involves the spinal cord ONLY and thus the response is quick and involuntary Example: touching a flame Reflex Arc Parthway: Sensory receptor
Sensory Neuron
Interneuron
Motor Neuron
Effector Impulse Transmission (Excitatory) 1. Resting Potential A positive outside and negative inside MUST be created across the axon’s membrane BEFORE it can transmit an impulse! Created by the sodium-potassium pump that pumps 3 Na+ out of the cell for every 2 K+ in (requires ATP) This difference in charge creates a voltage of -70 mV when measured with a voltmeter The axon membrane is described as polarized. Impulse Transmission (Excitatory) 2. Action Potential As the impulse starts moving down the axon, the axon’s permeability changes in that Na+ starts to moving into the axon to create an axon with a positive inside and negative outside Called a wave of depolarization or depolarized membrane. This occurs ONLY at the nodes of Ranvier as the myelin sheath insulates the axon it encircles Impulse Transmission (Excitatory) 3. Repolarization Na gates close, K gates open K ions diffuse out of the axon making the inside more negative, outside more positive After the impulse passes through the axon, the Na+ and K+ are on opposite sides of the axon. Thus, the sodium-potassium pump restores the resting membrane potential by pumping 3 Na+ out for every 2 K+ in Every axon must repolarize BEFORE it can transmit a second impulse!  Threshold Level The minimum amount of an impulse needed to get an action potential (response) Each neuron has a different threshold level If the impulse exceeds the threshold the response is the SAME….called the ALL or NONE RESPONSE Stimulus Muscle Contraction 1 mV -- 2 mV -- 3 mV 5N 4 mV 5N Synapse Once an impulse reaches the synapse, the Synaptic knob releases acetylcholine Attaches to receptors on the dendrites of the post-synaptic neuron Causes depolarization of the post-synaptic neuron so the impulse continues Acetylcholine is then broken down by cholinesterase (released by the dendrites of the post-synaptic neuron) Repolarization is allowed to occur Other random bits of information: Stimuli Intensity is detected 2 ways: The more intense the stimulus, the higher the frequency of impulses Each neuron has its own threshold level. The more impulses that reach the brain, the stronger the response. A neuromuscular junction is a synapse between a motor neuron and a muscle cell (works in much the same way) The Refractory period is the time it takes a neuron to repolarize (no other impulses may be passed during that time) Summation occurs when acetylcholine is needed from 2 or more neurons to cause depolarization of the post-synaptic neuron Hyperpolarization of an axon inhibits impulses from being transmitted when outside of the axon becomes more positive than normal due to an accumulation of K+ leaking outside the axon. As a result, getting enough Na+ inside the axon for depolarization is almost impossible. (Na/K pump restores resting potential) NS Question #1 NS Question #2 NS Question #3 NS Question #4 NS Question #5 NS Question #6 NS Question #7 NS Question #8  Autonomic Nervous System (involuntary) Sympathetic Parasympathetic Prepares body for stress Returns body to normal Effects include: Effects include:  Increased heart rate  Decreased heart rate  Increased release of  Release of epinephrine stops epinephrine  Decreased breathing rate  Increased breathing rate  Decreased metabolism  Increased metabolism  Decreased blood flow  Increased blood flow (vessels constrict) (vessels dilate)  Pupils constrict  Pupils dilate  Increased peristalsis  Decreased peristalsis  Stores glucose in liver and (digestion) muscles  Increased conversion of  Bladder sphincter contracts glycogen to glucose  Bladder sphincter relaxes Central Nervous System (CNS) Brain is protected by skull and 3 protective membranes called meninges Cerebrospinal fluid (CSF) circulates between the meninges and the central canal of the spinal cord Function of the CSF is shock absorber and transport of nutrients and wastes Level of brain development makes humans unique Spinal Cord Connects sensory and motor nerves to brain Contains white matter (myelinated from oliogodendrocytes) and grey matter (unmyelinated)….will these nerves regenerate??? Why or why not???? Brain - Forebrain Contains the following: Cerebrum (2 hemispheres) – largest and most highly developed part of the brain. Controls speech, reasoning, memory, personality, stores sensory information and imitates motor activity. Made of 4 lobes: Frontal – front of head. Responsibility for personality and higher level cognitive functioning Parietal – top of head. Responsible for touch, taste and pressure Occipital – back of head. Responsible for vision Temporal – near temples. Responsible for hearing and smell Midbrain Contains the following : Cerebral Cortex – covers the cerebrum. Made of grey matter and is highly folded to increase the surface area Corpus Callosum – allows the two hemispheres to communicate Thalmus – below the cerebrum. Coordinates/interprets sensory information Hypothalamus – below thalamus. Coordinates endocrine function. Pituitary Gland – connected to hypothalamus, hangs like a pendant on a necklace. Links nervous and endocrine systems. Hindbrain Joins with the spinal cord. Contains the following: Cerebellum – coordinates muscle movement. Beneath cerebrum. Medulla Oblongata – joins spinal cord to cerebellum. Controls all vital functions (Autonomic NS) Pons – relay station between medulla and cerebellum Right side of brain controls left side of body and vice versa NS Question #9 NS Question #10 NS Question #11 NS Question #12 NS Question #13 NS Question #14 Senses Sensory receptors pick up information from our environment and send this information to our brain along sensory neurons Sensation occurs when neural impulses arrive at the cerebrum Each persons unique perception results from how the cerebellum interprets the meaning of the sensory information Sensory adaptation occurs when the receptors have adjusted to changes in the environmental stimuli Taste and Smell Work together (eg. A cold) Taste sensory receptors are located on the tongue as taste buds Smell sensory receptors are olfactory cells in the nose. Airborne particles cause depolarization of the olfactory cells. They exhibit sensory adaptation. Touch Sensory receptors located all over the body. Many are concentrated in the genitals, fingers, tongue and lips. Sensitive to touch, pressure, pain and high/low temperatures Vision Structure – 3 layers 1. Sclera – outer layer that supports/protects the inner layers Cornea – transparent and bends light towards pupil. Receives oxygen from the gases dissolved in tears (no blood vessels because they would distort vision) Aqueous Humor – transparent fluid behind cornea that supplies nutrients to cornea 2. Choroid – middle layer (dark black color, contains blood vessels) Iris– muscle that controls the size of the pupil and thus the amount of light entering the eye Lens– behind the iris. Focuses the image on the retina. Ciliary muscles change the shape of the lens. Vitreous Humor– jelly like fluid-filled chamber behind the lens. Maintains the shape of the eye 3. Retina – inner layer. Contains 2 sensory photoreceptors. Rods– used when viewing in dim light, concentrated in periphery Cones– used for color vision and bright light Fovea Centralis– center of the retina and most sensitive. Contains cones ONLY and rods surround on periphery Blind Spot– where the optic nerve attaches to retina. Contains NO rods or cones. Focusing an Image Light enters the eye through the pupil whose size is controlled by the iris Light is bent by the cornea towards the pupil/lens Lens changes its shape as it bends the light onto the retina (inverted image) Rods/cones are the sensory receptor and when hit by light generate a nerve impulse down the optic nerve, through the optic chiasma to the occipital lobe  The lens’ ability to change its shape when viewing near/far objects is called the accomodation reflex Close objects – ciliary muscles contract and htus the lens thickens. The pupil constricts to focus the image on the retina Far objects – ciliary muscles relax and the lens thins. Pupil dilates to increase the amount of light entering the eye. As we age, protein builds up on the lens and thus is less flexible to accommodate when viewing close objects Vision Defects = STS Glaucoma – buildup of aqueous humor and thus the fluid pressure causes blood vessles to collapse and oxygen and nutrients decrease. Result is neuron death and blindness Cataracts – lens/cornea is cloudy and thus light cant pass through. The lens can be replaced Astigmatism – abnormal curvature of the lens/cornea Myopia/nearsightedness – eyeball is too long and thus image is focused in front of the retina. Corrected with a concave lens Hyperopia/farsightedness – the eyeball is too short and thus the image is focused behind the retina. Corrected with a convex lens Colorblindness – 1 or more type of cone is missing/defective. Most common is red-green colorblindness and is most common in males as the gene is carried on the X chromosome. Hearing The hear has two functions – hearing and balance Structures: 1. Outer ear – air filled Pinna – Funnels sound vibrations into auditory canal Auditory Canal – carries sound waves to the eardrum. Contains wax to trap foreign particles 2. Middle Ear – Air filled Tympanic membrane/eardrum – vibrates and passes sound waves to ossicles Ossicles– 3 tiny bones that amplify sound waves. These amplified sound waves are then passed onto the oval window membrane and then the round window membrane  Malleus/Hammer  Incus/Anvil  Stapes/Stirrup Eustachian Tube– equalizes air pressure between internal and external ear. Has no function in hearing! 3. Inner Ear – contains fluid filled structures Vestibule – connected to the oval window at the base of the semi-circular canals. Function is balance and head position (static equilibrium) Semicircular canals– attached to the vestibule. Function is balance and body position (dynamic equilibrium) Cochlea – contain specialized hair cells that convert amplified sound waves vibrations into electrochemical nerve impulses Cochlea Contains the Organ of Corti (actual hearing apparatus) that is composed of hair cells attached to a basilar membrane. When fluid moves due to amplified sound vibrations, hair cells bend due to the movement of the basilar membrane. Cochlea is protected by loud noises in two ways Muscles connected to malleus contract thus restricting its movement as it passes vibrations on Muscles of the ossicles contract so stapes is moved away from the oval window. Cochlea con’t Cochlea detects different pitches when different areas are stimulated STS – two types of hearing loss:  Nerve Deafness – damage to hair cells  Conduction Deafness – damage to the sound conduction system of the outer/middle ear Nerve pathway = Cochlea
Auditory Nerve
Temporal Lobe Balance/Equilibrium Static/Gravitational Equilibrium (head position) – contains 2 fluid filled sacs that contain hair receptors. The sacs are the saccule and utricle. The sacs contain otoliths (tiny stones) so when we move our head, the stones move and bend hairs which stimulate sensory nerves to the brain Dynamic/Rotational Equilibrium (body position) – fluid filled semi circular canals. The movement of the fluid causes hair cells to move and therefore initates nerve impulses to the brain. Motion sickness is the continuous movement of fluid. Senses #1 Senses #2 Senses #3 Senses #4 Senses #5 Senses #6 Senses #7 Senses #8 Senses #9 Senses #10  Endocrine System Endocrine Glands Exocrine Glands Ductless Ducts (tubes) Maintain control for a Examples include sweat longer duration and salivary glands Examples include adrenal glands, pituitary gland and thyroid gland What is an example of BOTH and exocrine and endocrine gland? Types of Hormones Steroid Hormones Protein Hormones Made of cholesterol Made of amino acids Fat soluble Water soluble Attach to receptors in Attach to receptors on cytoplasm (inside cell) cell membrane Examples include sex Examples include hGH hormones and cortisol and thyroxin Homeostasis- (+) & (-) feedback Hypersecretion = too much of a hormone being released Hyposecretion = not enough of a hormone being released Usually the diploma will give a function of a hormone and then ask which gland produces the hormone described so you need to be able to identify the hormone and then the gland Glands and Hormones Pituitary (master gland) Made of 2 lobes: Posterior lobe – stores and releases hormones produced by the hypothalamus Anterior lobe – produces and releases its own hormones. Regulated by hypothalamus NOTE: The diploma will not ask you to differentiate the hormones produced by the anterior and posterior lobes Human Growth Hormone (hGH) Affects all cells, especially cartilage and bone cells At puberty : A hypersecretion causes GIGANTISM A hyposecretion causes DWARFISM We will talk about the rest of the pituitary hormones during the Reproduction lesson. Adrenal Glands a) Adrenal Medulla (inner gland) Regulated by nervous system Produces norepinephrine (sustain BP) and epinephrine during stress. Functions are sympathetic NS responses: Increased blood sugar Increased heart rate Increased breathing rate Increased metabolism Blood vessels dilate Pupils dilate Peristalsis stops NOTE: The diploma will not ask you to differentiate between hormones produced by the adrenal medulla and cortex Adrenal Glands b) Adrenal Cortex (outer gland) Small amounts of sex hormones Aldosterone Increased Na+ reabsorption into blood. Released when blood volume and BP are low Cortisol (LONG TERM stress) Amino acids/fats are converted into U Testosterone in females and estrogen in males Antidiuretic Homrone (ADH) Produced by Posterior Pituitary Makes nephron (kidney) permeable to water so water can be reabsorbed back into the blood Released when the body is dehydrated and needs to conserve body water Produces a concentrated urine Diabetes Insipidus – body can’t produce enough ADH Negative Feedback loop for Release of Cortisol Endocrine #1 Endocrine #2 Endocrine #3 Endocrine #4 Endocrine #5 Pancreas (Islets of Langerhans) a) Insulin Released from beta cells when blood sugar levels are high Makes cells permeable to glucose and converts glucose into glycogen in the liver and muscles Effect on blood glucose levels??? b) Glucagon (all the glucose is gone) Released from alpha cells when blood sugar levels are low Converts glycogen into glucose Effect on blood glucose levels??? Diabetes Mellitus Symptoms of Diabetes Mellitus: Glucose in urine (sweet urine) High urine output Low energy levels Thyroid Gland Located in front of trachea Produces 3 hormones: Thyroxine Triiodothyronine Calcitonin Thyroxine and triiodothyronine regulate metabolism (rate of cellular respiration) Thyroxine decreases blood sugar levels because it increases metabolism Hypothyroidism Release low amounts of thyroxine What happens to excess glucose that can’t be broken down? Symptoms include: Weight gain Tired Sensitive to cold Dry skin Treatment?? Goiter An enlarged thryroid gland due to lack of iodine in diet (component to make thyroxine). As a result, production of thyroxin is decreased. Thyroid increases in size due to build up of TSH in the thyroid gland Negative feedback loop for normal thyroxine release Hyperthyrodism Release high amounts of thyroxine Symptoms include: Sweating Anxiety Weight loss Heat intolerant Racing heart Bulging eyes Graves disease (in children) Treatment?? Calcitonin Released when blood Ca2+ levels are HIGH 3 functions: Increase Ca2+ excretion from kidneys Decrease Ca2+ release from bones Decrease Ca2+ absorption from small intestines Effect on Ca2+ levels??? Parathyroid Gland Located on top of the thyroid gland Releases Parathyroid Hormone (PTH) when blood Ca2+ levels are LOW 3 functions: Decrease Ca2+ excretion from kidneys Increase Ca2+ release from bones Increase Ca2+ absorption from small intestines Effect on Ca2+ levels? Prostaglandins Hormones that have an effect on a small localized area Endocrine #6 Endocrine #7 Endocrine #8  Endocrine #9 Endocrine #10 Endocrine #11 Endocrine #12 Endocrine #13 Endocrine #14  Endocrine #15 Endocrine #16 Answers to Practice Questions Nervous System 1. C Endocrine 2. D 1. A 3. 4231 4. 9040 (for THAT neuron – need to look at graph) 2. 124 5. A 3. 3214 6. A 4. B 7. C (reflex) 5. B 8. D 6. D 9. C 7. C 10. A 8. A 11. D 9. C 12. C (fear is an adrenaline type sympathetic 10. C response) 11. A 13. A 14. A 12. B Senses 13. B 1. B 14. A (C is not direct) 2. B 15. B 3. 134 (or 314, order no longer matters on 16. A (both groups don’t get caffeine, so diploma, but read instructions carefully) that would be different. Dopamine 4. D is responding variable, not control) 5. 3142 6. B 7. C 8. 1235 9. C 10. 3256 Unit A: Nervous and Endocrine Systems Questions? Comments? Next is Unit B – Reproduction and Development